Technical Field
[0001] This invention relates to a wiper apparatus for wiping a windshield of an automobile,
and more particularly to improvements on a retractable type wiper apparatus the wiper
blade of which is adapted to be retracted or concealed from view when not in use.
Background Art
[0002] Japanese Utility Model Application Public Disclosure (Kohkai publication) No. 59-190648
discloses a typical retractable wiper apparatus of the type described, as shown in
Figs. 20 to 22 attached to the present application.
[0003] More specifically, the prior art wiper apparatus illustrated therein comprises a
first crank 2 connected to and locked by a nut 4 to an output shaft 1 of a reducer
which is in turn connected to a wiper motor, and a second crank 3 which is secured
to the first crank by means of a first' pivot shaft 5 projecting from the second crank
and a nut 6. The first crank 2 is formed with stop shoulders 7 and 8 having locking
recesses 7a and 8a, respectively. Secured to the second crank 3 is a second pivot
shaft 9 over which a cam 10 is fitted. A bearing 11 is also fitted over the pivot
shaft 9 and secured integrally to the cam 10. A first link 12 is secured to the bearing
11 by means of a socket 13 which is connected to the link 12 and adapted to receive
the bearing 11.
[0004] A wiper blade 14 is supported by an arm 15 which is secured at a pivot 16 to a second
link 17 which is in turn connected to the first link 12. A detent 18 engageable with
locking recesses 7a, 8a is slidably mounted in a guide frame 20 and is biased outwardly
by a spring 19. The frame 20 is fastened to the second crank 3 by screws 21.
[0005] During the normal wiping operation the motor output shaft 1 is rotated in the forward
direction of rotation as indicated by the arrow P. The rotation of the first crank
2 in this direction causes the second crank 3 connected by links 12 and 17 to the
wiper arm 15 to be relatively rotated about the pivot shaft 5 due to the rotational
resistance of the second crank until the second crank is bent relative to the first
crank and comes into abutment with the stop shoulder 8 of the first crank 2, whereupon
the detent 18 is urged into the recess 7a to lock the second crank to the first crank
at said bent-angle. While angled relative to the first crank 2 as shown in Fig. 22,
the second crank 3 is thus rotated about the output shaft 1 in the direction P, whereby
the pivot pin 16 is moved in its reciprocal rotating motion by means of the links
12, 17 to operate the wiper blade 14 for wiping action.
[0006] The range in which the wiper blade is reciprocally moved with the second crank 3
angled relative to the first crank 2 is a normal range of operation. Upon the wiper
motor being deenergized, the wiper blade is stopped at the extreme end A of the range
of operation by an automatic stopping - at - fixed position mechanism (not shown).
[0007] When it is desired to stow away or retract the wiper arm from its normal stop position,
the wiper motor is driven in the reverse direction, so that the first crank 2 is rotated
in a direction opposite from that indicated by the arrow P. The second crank 3 which
is connected to the wiper blade by means of the links is caused to relatively rotate
about the pivot shaft 5 due to the rotational resistance until the crank 3 comes into
abutment with the stop shoulder 7 of the first crank 2 to assume the straight extended
position whereupon the detent 17 is urged into the recess 8a to lock the second crank
at its extended position.
[0008] The effective length of the cranks when the second crank 3 is extended straight relative
to the first crank 2, that is, the distance between the two shafts 1 and 9 is longer
than the distance between the two shafts 1 and 9 when the second crank is at its angled
position, so that the wiper blade at its normal stop position A in Fig. 22 is retracted
beyond its normal range of operation into the retracted or concealed position B.
[0009] During the wiping and blade retracting operations the cam 10 fitted over the pivot
shaft 9 of the second crank 3 is rotated in unison with the link 12. The cam 10 is
adapted to press and lock the detent 18 which is in engagement with the recess 7a
during the forward rotation for the wiping operation and to disengage from the detent
upon reverse - rotation through some degrees of angle (about 35°) after the normal
rotation (180°) and press and lock the detent 18 as it is engaged with the recess
8a when the second crank 3 is completely extended relative to the first crank.
[0010] While the prior art retractable wiper apparatus described above is capable of retracting
the wiper blade from the normal stop position into the retracted position by means
of the relatively simple mechanism, during the normal continuous driving of the motor
(wiper operation) with the second crank 3 bent at the predetermined angle relative
to the first crank 2 such condition occurs once per rotation that the cam 10 is disengaged
from pressing contact with the detent 18. In such condition there is instability in
operation in that the biasing force of the spring 19 alone is relied on for urging
the detent 18 into the recess 7a of the stop shoulder 7. As a result, play or creaking
tends to occur, causing clattering at the tip of the wiper blade and making the automobile
driver feel uneasy.
[0011] Briefly, the present invention provides a retractable type wiper apparatus comprising
a first crank connected to an output shaft of a reducer of a wiper motor; a second
crank rotatably secured to the first crank by means of a first pivot shaft and so
arranged that the second crank is kept bent at a predetermined angle relative to the
first crank during the rotation of the first crank in the forward direction, and kept
extended substantially straight relative to the first crank during the rotation of
the first crank in the reverse direction; a detent slidably mounted in the second
crank and adapted to be resiliently urged into a first recess and a second recess
in the first crank to thereby lock the second crank in place when the second crank
is positioned at the predetermined angled and at the straight extended position, respectively
relative to the first crank; link means rotatably connected to the second crank by
means of a second pivot shaft for transmitting the motion of the second crank to a
wiper blade; and cam means rotatably mounted over the second pivot shaft and adapted
to press and lock said detent as it is urged into either said first or second recess;
characterized in that said cam comprises two superposed cam members both engageable
with said detent, one of the cam members being connected integrally with said link
means and the other of the cam members being adapted to be moved together with the
one cam member with.a limited range of lost motion so that the two cam members are
maintained at such angles relative to each other that they cooperate to press and
lock said detent during the rotation of said first crank in the forward direction.
Disclosure of Invention
[0012] Accordingly, it is an object of this invention to provide an improved retractable
wiper apparatus in which the cam means for pressing and locking the detent in place
comprises two cam members cooperating to always maintain the detent in its pressed
and locked position during the rotation of the output shaft of the reducer in the
forward direction (wiping'operation) whatover angular position the cams may be at
whereby there may be no chattering or creaking during the wiping operation.
Brief Description of the Drawings
[0013] The features and advantages of the present invention will be more fully disclosed
in the following specification with reference to the accompanying drawings, in which:
Fig. 1 is a longitudinal cross-sectional view of the principal part of the retractable
type wiper apparatus according to one embodiment of the present invention;
Fig. 2 is a plan view of the wiper apparatus shown in Fig. 1;
Fig. 3 is an exploded perspective view of the wiper apparatus shown in Fig. 1;
Fig. 4A is a perspective view of the cam means according to the present invention
illustrating the two cam members at the same angular position;
Figs. 4B and 4C are plan views of the first and second cam members of the cam means
shown in Fig. 4A, respectively;
Fig. 5A is a view of the cam means similar to Fig. 4A but illustrating the cam members
at different angular positions;
Figs. 5B and 5C are plan views of the first and second cam members of the cam means
shown in Fig. 5A, respectively;
Figs. 6A - 11A and 6B - 11B are diagrammatic views illustrating the successive steps
of the wiping operation by the wiper apparatus;
Figs. 12A - 16A and 12B - 16B are diagrammatid views illustrating the successive steps
of the retracting operation of the wiper apparatus;
Fig. 17 is a longitudinal cross-sectional views of the principal part of the retractable
type wiper apparatus according to an alternate embodiment of the invention;
Fig. 18 is a plan view of the wiper apparatus shown in Fig. 17;
Fig. 19 is an exploded perspective view of the wiper apparatus shown in Fig. 17;
Fig. 20 is a longitudinal cross-sectional view of a prior art retractable type wiper
apparatus;
Fig. 21 is a plan view of the wiper apparatus shown in Fig. 12; and
Fig. 22 is a diagrammatic view illustrating the wiper apparatus in operation.
Detailed Description of the Preferred Embodiments
[0014] An embodiment of the present invention will now be described with reference to Figs.
1 to 3 in which components of the wiper apparatus of this invention which are similar
to corresponding components of the prior art wiper apparatus described hereinabove
and shown in Figs. 20 - 22 are designated by the same reference numerals as in the
prior art apparatus.
[0015] The wiper apparatus according to this invention comprises a first crank 2 connected
to and locked by a nut 4 to an output shaft 1 of a reducer (not shown) which is in
turn connected to a wiper motor (not shown), and a second crank 3 which is secured
to the first crank 2 by means of a first pivot shaft 5 projecting from the second
crank and a nut 6. The first crank 2 is formed with stop shoulders 7 and 8 having
locking recesses 7a and 8a, respectively. Secured to the second crank 3 is a second
pivot shaft 9 over which cam means comprising two stacked cam members 30, 31 is rotatably
mounted. A bearing 11 is integrally connected with the upper cam member 30 of the
cam means and is also fitted over the pivot shaft 9. A first link 12 is securedly
connected to the bearing 11 by means of a socket 13 adapted to receive the bearing
and having slots 13a for receiving connecting pins lla projecting from the bearing
to prevent relative rotational movement between the socket and bearing. A snap ring
13b is mounted on the shaft 9 to retain the bearing 11 in place.
[0016] The cam members 30 and 31 are formed around its periphery with two notches 30a, 30b
and 31a, 31b, respectively spaced apart from each other by a displacement angle 6
of 120° as shown in Figs. 4A - 4C and SA - 5C. The upper cam member 30 connected integrally
with the bearing 11 is further formed with a concentric arcuate slot 30C extending
through a lost-motion angle of 60°. The lower cam member 31 has a projection extending
therefrom and adapted to be inserted into the arcuate slot 30C.
[0017] The wiping operation of the wiper apparatus constructed as described above will be
described with reference to Figs. 6A - 11A and 6B - 11B.
[0018] Figs. 6A and 6B illustrate the wiper blade 14 stopped at the retracted position B
wherein the second crank 3 is extended straight in axial alignment with the first
crank 2. The notches 30a, 30b and 31a, 31b of the cam members 30 and 31, respectively
are in alignment with each other, and the aligned notches 30a, 31a are in an angular
position opposing the detent 18, so that the detent, released from the locking action
by the cam members 30, 31, is urged into the locking recess 8a by the biasing force
of the spring 19 alone.
[0019] Figs. 7A and 7B illustrate the first crank 2 rotated through about 30° by the driving
of the wiper motor in the forward direction, whereby the detent 18 is dislodged from
the recess 8a and urged into the recess 7a with the second crank 3 bent at the corresponding
angle relative to the first crank 2.
[0020] Figs. 8A and 8B illustrate the first crank 2 further rotated through about 60°, whereby
the cam member 30 is rotated through a corresponding angle while the projection 31C
of the second cam 31 relatively moves along the arcuate slot 30C from one end to the
other end thereof where there is a displacement in phase between the notches 30a,
30b of the cam member 30 and the notches 31a, 31b, whereby the two cam members cooperate
to define a complete circular cam to lock the detent 18 in place.
[0021] Thereafter, the cam members 30 and 31 will be rotated . in unison while maintaining
the detent 18 locked.
[0022] Figs. 9A and 9B illustrate the wiper blade 14 having arrived at one extreme end C
of the wiping movement, from which the wiper blade is reversed in its direction of
movement.
[0023] Figs. 10A and 10B illustrate the wiper blade being rotated in the reverse direction.
[0024] Figs. 11A and 11B illustrate the wiper blade 14 having reached the other extreme
end A of the wiping movement which is the point of reversal for the normal wiping
operation.
[0025] Next, the operation for stowing the wiper blade to the retracted position will be
described with reference to Figs. 12A - 16A and 12B - 16B.
[0026] When it is desired to retract the wiper blade to the recessed position B, a switch
(not shown) disposed in an electric power supply circuit (not shown) is thrown into
an "off" position, said circuit having an automatic stopping - at - fixed position
mechanism and a reversing mechanism for the wiper motor. Upon the switch being moved
into the off position, the wiper motor is continued to be rotated in the forward direction
under the control of the circuit until the wiper blade 14 is moved from the position
A back to the position C whereupon the motor is reversed.
[0027] Figs. 12A and 12B illustrate the wiper blade 14 moved back to the point of reversal
C where the wiper motor is reversed to rotate the output shaft 1 in the reverse direction.
[0028] Figs. 13A and 13B illustrate the first crank 2 rotated through about 60° by the reverse
rotation of the output shaft 1. In this position the notches 30a, 30b and 31a, 31b
of the cam members 30 and 31, respectively are in alignment with each other, and the
aligned notches 30b, 31b are in an angular position opposing the detent 18, so that
the detent is released from the locking action by the cam members.
[0029] Figs. 14A and 14B illustrate the detent 18 dislodged from the recess 7a and urged
into the recess 8a while the second crank 3 is disengaged from the stop shoulder 8
and brought into abutment with the stop shoulder 7 so that the first and second cranks
are straightened in longitudinal alignment.
[0030] Figs. 15A and 15B illustrate the first and second cranks 2, 3 further rotated in
the reverse direction until the wiper blade 14 has.reached the extreme end A of the
normal wiping movement.
[0031] Figs. 16A and 16B illustrate the first and second cranks 2, 3 in their straightened
position continuing to rotate until the wiper blade 14 has been moved from the extreme
end A of the wiping movement to the retracted position B. Upon the blade 14 reaching
the retracted position, the automatic stopping - at - fixed position mechanism is
actuated to stop the wiper motor. When the wiper blade 14 is thus moved to the retracted
position B by the reverse rotation of the output shaft 1, the notches 30a, 30b and
31a, 31b of the cam members 30 and 31, respectively are aligned with each other, and
the aligned notches 30a, 31a are in an angular position opposing the detent 18 to
release the locking action on the detent.
[0032] It is thus to be understood that the cam means for locking the detent which serves
to join the first and second cranks 2, 3 comprises two cam members and that the two
cam members are arranged to cooperate during the wiping operation to maintain said
detent in its locked position irrespective of the angular position of the cam members,
whereby it is assured that no play or creaking occurs in the crank mechanism during
the wiping operation.
[0033] While in the illustrated embodiment the angle of displacement between the notches
30a, 31a and 30b, 31b of the cam members 30 and 31 is shown as 120°, the angle of
arc (lost motion) of the arcuate slot 30C of the cam member 30 is shown as 60°, and
the bent angle between the first and second cranks 2, 3 is described as 30°, these
angles may be varied depending upon the amount in which the wiper blade is to be retracted.
[0034] Figs. 17 to 19 show an alternate embodiment of the wiper apparatus of this invention,
in which component portions of the wiper apparatus which are similar to corresponding
portions of the wiper apparatus shown in Figs. 1 - 16 are designated by the same reference
numerals as in the first embodiment.
[0035] Only those component portions of the apparatus according to this alternate embodiment
which are different from corresponding portions of the first embodiment will be designated
by new reference numerals and described below.
[0036] In this modified embodiment, an arcuate stop member 33 is fitted at its opposite
ends over a pair of spaced apart pins upstanding from the first crank 2, in substitution
for the stop shoulders 7 and 8 in the first embodiment. The stop member 33 is further
secured by a screw 34. The straight extended position and the angled position that
the second crank assumes relative to the first crank 2 are determined by an extension
3a of the second crank abutting against the opposite ends of the stop member 33 adjacent
the pins 32. In addition, the arcuate stop member 33 is formed adjacent the opposite
ends thereof with a pair of spaced locking recesses 7a and 8a for receiving the detent
18 at its angled and straight extended positions, respectively.
[0037] It will be appreciated that the wiper apparatus according to this modified embodiment
will provide the same functional advantages as the first embodiment does.